This invention relates to a Wakeup-On-LAN (WOL) detector and a method for use in local area networks in which specific network client station(s) can be awakened from a power down or sleeping state by receipt of a packet addressed to the specific station(s). The architecture selected for implementing the WOL function permits the WOL pattern to be inserted in a variety of locations in the pay load field of a frame within which it is transmitted. This allows the WOL pattern to start in a byte which may be either aligned with or not aligned with a data word boundary.
In order to improve performance, WOL frames are processed in two byte words using a sixteen bit internal bus. No problem exists when the WOL pattern starts on a word boundary. However, if the pattern starts in the middle or odd byte of a two byte word, a conventional two byte detection process will not work.
The invention contemplates a detector responsive to a received data frame which includes as part of its payload, a first signal F . . . F for indicating a wakeup condition and a second signal DA . . . DA for identifying a specific device. A detector responsive to the frame and the F . . . F signal provides a control signal indicating the relative position of the DA . . . DA signal with respect to the F . . . F signal. The DA . . . DA signal is handled by a first processing means when the relative position of the DA . . . DA signal and the F . . . F signal are in a first state and by a second processing means when the relative position is not in the first state. If either processing means detects a valid DA signal, a wakeup condition is identified.